1. Field of the Invention
The present invention relates to motor control in an apparatus equipped with a motor, such as a recording apparatus.
2. Description of the Related Art
Examples of apparatuses equipped with a motor include a recording apparatus and an image reading apparatus. In the recording apparatus, a recording head is driven by a motor. In the image reading apparatus, a reading unit is driven by a motor. The drive force of the motor includes a so-called torque ripple (i.e., cogging torque, hereinafter referred to as “cogging”). Due to this cogging, the rotational speed of the motor includes fluctuation of speed according to a cogging period. The recording head and the reading unit are attached to a member such as a belt, and are caused to move (scan) by a movement of the belt.
Japanese Patent Application Laid-Open No. 2008-211869 discusses a technique of making a correction by performing feedback (FB) control based on a difference between an actual speed and a target speed of a driven object, and further performing feed forward (FF) control for adding correction information based on speed information of previous motor driving operations.
Japanese Patent Application Laid-Open No. 2003-260842 discusses a technique for correcting a deviation of a carriage speed generated due to elongation and contraction of a belt at the time of carriage acceleration control and deceleration control.
However, since the recording apparatus and the image reading apparatus are affected by elongation and contraction of the belt, the speed control using the techniques discussed in Japanese Patent Application Laid-Open Nos. 2008-211869 and 2003-260842 cannot eliminate a speed change caused by the cogging.